Injection pump



.und

March 27, 1956 w. volT ET AL 2,739,643

INJECTION PUMP Filed 0013. 25, 1954 v United Stareg patm,

INJECTION PUR/i1 Willy Voit, Stuttgart-Bad Caunstadt, and Ulrich Aldingerj Stuttgart, Germany, assignors to Robert Bosch G. m. h. H., Stuttgart, Germany Application October 2S, 1954, Serial No. 46ft,8-1

Claims priority, application Germany November 17,1953

8 Claims. (Cl. 15S-36.4)

One of the objects of the present invention is to provide an injection pump with a means for automatically delivering to the engine, when the latter is beingjstarlted, an amount of fuel greater than that received byJ the engine when the latter is operating at full load. l y

Another object of the present invention is to provide a fuel injection pump with a means for automatically de-y creasing, as the engine speed increases, the amount kof fuel delivered from the pump to the engine.

A further object of the present invention is to provide a fuel injection pump with a convenient, easily operable adjusting means for adjusting the extent towhich the amount of fuel, delivered from the pump to the engine, is changed with the automatic regulating means of the invention. i

An additional object of the invention is to provide a structure which is capable of accomplishing the above objects and which at the same time is made up of simple and ruggedly `constructed parts which are veryreliable in operation and to which an easy access is provided for maintenance purposes.

With the above objects in view the present invention mainly consists of an injection pump for an internal combustion engine, this pump including a pump housing formed in its interior with a cylindrical bore and having' in the pump housing means which form therein a fuel chamber separate from the cylindrical bore. A pump piston is slidable in the cylindrical bore, and a reciprocating means engages the pump piston to reciprocate the same between bottom and top dead center positions. A free piston is slidably mounted in the cylindrical bore for free movement therein and faces the head end of the pump piston so that the pistons define between themselves a pump chamber formed by that part of the cylindrical bore which is located between the pistons. A limiting means forms part of the housing and limits movement of the free piston toward the pump piston. A first passage means communicates with the fuel chamber and with a part of the pump chamber distant from the free piston for supplying fuel to the interior of the pump chamber when the pump piston moves in its suction stroke toward its bottom dead center position. A second passage means leads to a cylinder of the engine and communicates with a part of the pump chamber adjacent the free piston for delivering fuel from the pump chamber to the enginel cyly inder. A third passage means communicates with the fuel chamber and with a part of the bore located at the side of the free piston opposite from the pump piston so that the free piston is located between the third passage 5 ment in the same bore of block 2 which houses the piston means and the pump chamber. A passage control means is carried by the housing at the third passage means thereof for automatically opening the third passage means to an increasing Aextent as the engine speed increases and to a decreasing extent as the engine speed" decreasesuntil at low engine speeds the third passage means is closed and the free piston cannot move away from the pump piston, while at relatively higher4 engine speeds the free piston may move away from the pump piston, displacing fuel through the third passage means into the fuel chamber, to reduce the amount of fuel moved by the lpump piston through'the second passage means to the engine cylinder.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together withadditional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

Referring now to the drawing, which isa sectional elevational view through an injection pump constructed inl accordance with the present invention andV which shows schematically apparatus for delivering fuel to and removing fuel from the injection pump, ity will be seen that the injection pump of the invention includes a pump housing made up of housing parts 1, 2, and 3,l part 2 being a block which extends across the interior of the pump housing. A cam shaft 4 is rotatable within the housing part 1 and engages the bottom end of a pump piston 5 which is slidable within a cylindrical bore passing through the block 2. The end of piston 5 which engages thefcam shaft 4 is enlarged, and a spring is located about piston Sand abuts against the block 2 and the bottom enlarged end of f piston 5 to maintain the latter against the cam shaft 4.l

The block 2 forms with part 3 of the pump' housing a fuel chamber 25 to which fuel is supplied by a pump 26 which is driven by the engine so that the speed of the pump 26 varies directly with the speed of the engine. A passage means 8, in the form of a bore' in the block 2, leads from fuel chamber 25 to the interior of the cylindrical bore in which the pump piston S reciprocates. Thus, when the pump piston 5 moves down to its bottom dead center, the bottom right end of bore S, as viewed in the drawing, lwill become uncovered and fuel will How into the cylinder of block-2 which houses the piston 5 ahead of this piston to be moved by piston 5 during its pressurestroke. The piston 5 is provided with a control surface 6 formed with a groove extending axially along piston 5 from its head end and communicating with an annular` Agroove'extending about the piston S and defined in part by the helical edge 7. The block 2 is' formed with a passage 9 ,leading from the cylinder of block 2 which houses piston 5 to the threaded bore 43 from which a conduit leads to a fuel tank 44, this tank 44 communieating through a suitable conduit with the suction sidev of pump 26. Thus, fuel ahead of the piston S will be moved thereby until edge 7 uncovers passage 9, and thenl the remaining fuel will ow through the passage 9 back to the tank 44. The piston 5 is formed with axially extending teeth which mesh with a manually operable rack 47, so that the operator by pushing or pulling rack 47 regulates the angular position of piston S so as to control the moment in the stroke of piston 5 at which the return flow passage 9 is uncovered by edge "l.

-A free piston 16 is mounted for free sliding move- Patented Mar. 27, i956 5, and this bore has a larger cross section at the part thereof which houses the free piston 10Y so thattheblock 2 is provided with a shoulder forming a limiting means which limits the movement of the free piston. 10 toward the pump piston 5, these pistons forming between themselves a pump chamber 12 which is in communication with a discharge passage means 13 communicating with pump chamber 12 at a part thereof adjacent the free piston 10.. Thus, fuel in the chamber 12 will be moved, during the pressure stroke of piston andbef'ore 'passage 9 is uncovered, through the passage means 13 and through a non-return valve 14 to an enginefcylinder. A spring 11 engages: the free piston 10` and urges: the. latter. to its illustrated position Where it islocated against.` the shoulder and is nearest to the pump pistons.'

As the pump piston 5 moves in its pressure. stroke the fuelin pump chamber 12 tendsl to move freepi'ston 1 0. against the inuence of spring 11 away from pump piston '5, and this latter movement of free pistonI 10 islimited byy an elongated stop. member 15. extendingvv into the bore ofblockA 2 which houses the f ree. piston 1 0; The housing part 3 is formed. in. its. top wall'fwith. a threaded Vbore which threadedly carries a. tubular mem-. ber, 2 7 formed in its interior with threads in. threaded engagement with outer. threads von the. top end portion.

of stop member 15 which. extends. through themernber 2 7. tothe exterior of the pump, the top. freeA end. of theV stop member 1 5 being provided with a slot to receive a. screw driver or the like. so that theA operatonmay turn s .topmember 15 to adjust the distancebetween,` the stop member and. the free; piston when the, latter is in the positionshown in the drawing so as to regulate.. the. extentl to which the free piston 10 can. move. away. from thepump piston .5, a stop nut 28 being in threaded engagement with the' member 15 and engaging.v member 2 7. to" lock stop member 15 in its adjusted position. The, member makes a fairly tight t with the. bore 'of block 2. which. houses the free piston 1 .0 so that therey can be no leakage past the stop member-15 intooroutof the block 2.

T The elongated stop member 15 is formed in its interior. with an axially extending bore having. a. portion. 18 of relatively large crossr section into which springl 11 extends, an. intermediate portion 2 1 of a smaller c rpss section than portion 13 and forming a shoulder' 1 6, therewith,Y andl a top portionv 23 smallerY in .crosas ecfV tion thauportipn 2 1 and forming, a shoulder 17 therewithfthe stop, member 1 5 being provided with a cross` bore 2 4 communicating with bore portiony 23 and fuel chamber 2 5. A plate 1- 9V for-med. witha, central, aper-r ture. is1 o cate d againstshoulder.A 1 6, and spring 11. abutsf,A

against the. bottom facev o f plate 19, a springi20 abut-l ting against@ the Vtop face of plate 19, extending along', bore.,portiony 21, and urging a ball valve. member 2 2. againstv shonl der` 17 to close4 bore. portion 23, elementsinl-1111,21` forming a non-return v alve means allow.

ing, fuel to ow from chamber into chamber 4 2, between. stop 1S. and free piston. 10, when thel pressureon the downstream side ofA ball valve 22 is. lesst than the f uel pressurein chamber 25 by an amount. greater than the f orce of spring2.

The b1ock 2 is further formed. with, an elongated.v

bore 22- parallel to pump piston 2 5,A and. an elongated; control member 3 0, forming a passage controlrneansI asfwillbepointed o ut below, is slidable within.tlaelbore;` 2 9, A. springr31 is. located about an. upper. portion of;

member 30, abuis, with its-bottom end: against block 2,

and. engageswith. its. top end a washer 33. or the-1ilre. fixed: to thecontrol` memberv so that the; spring.` 3 1..- urges, the controlA member 30- upwardly, as viewed in-A the drawing, to thepositionv shown in ther drawing where the control member` 30 engagesV av stop, 32;,xed in.

ment: of control member 30. This control. memberl 3[t\is formed withA an. axially extending` bore. 3,4; having: inter-s of the bore portion and respectively leading into shown; in. the. drawing,

annulargrooves 38 and 39 formed in the .control niegue,l ber 30. 'Y

A passage means 40 is formed in the .block 2, extends across ythe bore 29, communicates with thebore which houses free piston 10 and stop 15, and communicates with thefuelchamber 25,A the. chamber 42, on the-side; of free piston 10 opposite from pump piston 5, thus communicating with passage' means 40; The return ow passage 9 also is intersected by the bore 29, and a further bore 45 is formed in. the block 2. and provides communication between bore 29 and the opening. 43 which leads to tanlc44.

When the engine is started up, the control, memberl 30 is located in the position illustrated. in. the drawing. At the'very low speeds of the engine, when 'it is.. starts ing, the fuel supply pump 26 supplies s uch. asmall, amountoffuel to the fuel chamber 25, that the throttlecl` portion 35 of the bore 34 does notcause the pressure in. the fuel chamber 25 to increase by an, amount suf iicient to causethe, control member 30 to move downward1y',as. viewedY in the drawing, against the inuence o f thespring 3 1. At this time the passage 9 as well as the Apassage 40 areA closed. by the. control member 3l) which. extends across thesev passages: in. the. manner The chambers 18 and 21 of stop,1 nember 1 5 as well as the chamber 42. are lled with fuel whichis supplied to these chambers fromcham berv.2 5.v through the non-return valve 22. vAs long as controlmember, 30 closespassage 40 the free piston 10=can no t5moveinto the chamber 42` from the position shown in thedrawing since fuel cannot be displaced from chain,- ber 42 throughv the passage 40. Whatever. fuel. is lost fromchamber 42 by leakage at this 'time is immediately mademp4 by fuel flowing into the, chamber 42 through the, valve, 22. Thus, at the time when theA engine'is, Started.. @wisten Pump 5 must Supply a. full measure ofg fuel. to thev engine, since with the control, member 3!),in the. illustrated position both passage 40: and pas sage 9 are .closed and the fuel supplied throughr `inlet 849111611411112 Chamber' is. necessarily moved; to the Passage 1 3. duties-111e,entireprcssur@ Stmk? Ofthe nis."- tengnumpf Tfheretcre. #1t-.the 10W Startins Speeds. ci;

@asesina a relatively; large mount of fuel is. Supnled'.

thereto This; large Supply v0f fuel isy many eases desirable-and 0.fgreat advantage. for.. Starting mimosas;

Thelfisl. which .flaws dirvuah the; passage 3.45m- @111ml member. 30, and, thus through the. throttledA portion, 3 5 thereof, flows; through. the; cross bore ,36 into, the; ane nular groove.; 3 8`ia'nd. from the latter through the bore 45.4 into the opening 43,'f-rom. where the fuel flows back t0. thetankt;

scones. ther-engine speed hasincreased. substantiallyaboye,th e.starting,speed thereof, the pressure of' the-fuel.. in,.9h.ambe.r. 25.l increases. This. pressure. increases because.;the fuel supplyY pump26., ,driven by;the,engin,opalsol increasesrin; speed and delivers a. greater. amount7 ofl fuel tothe@ chamber. 4.5: within. a. given, period ofI time,` so that therresult is. that the chamber 25.1".eceives. fuel. at. arate.

Whihds greatergthanthefgreatest possible rateofyowroffuel-.thro.ugh the. tbrottled portion 35, of the borel.. As

anesultfof.theincreasein pressure in chamber 25the controlzmember. 30 begins to .move1downwardl y,. ast-viewed. in.'t he.ld`r awing, against they nuence of. the springfBL at least through: a. distance. suflicient to. cause. fileedge 4.6

oiscontrol member; 3.0. to, uncover-passage 401. at: least:

' partly: and thus.:` control the. extent; of'; ow f of? fueltheref.

through. frornchamber 42:'to chamber- 252 'Ac thesamet.

arsaeas time the downward movement of control member 31 causes the annular groove 38 to overlap passage 9 and open the latter to the discharge opening 43. The position of control member 30 is rthus dependent on the speed of the engine.

At this time the pressure produced on the fuel in pump chamber 12 by piston S, during the pressure stroke of the latter, causes the free piston to move into the chamber 42 until the free piston 10 engages the stop 15', and in this way the free piston 10 displaces fuel from chamber 42 through passage il into the chamber 25. The supply of fuel to the cylinder of the engine thus starts at this time only after the free piston 10 has engaged the stop l5 and ends when the edge 7 of the piston 5 uncovers the return ow passage 9. Therefore, the maximum amount of fuel delivered to the engine during its normal operation, after the starting period, is determined by the position of stop 15. The best possible position of stop 15 may be determined by test for each engine, and the lock nut 28 maintains stop 15 in its adjusted position.

A change in the fuel supplied during operation, and therefore a change in the output of the engine, is obtained by turning the pump piston through shifting of the rack 47. Thus, in accordance with the angular position of piston 5 the edge 7 will uncover the return flow passage 9 at a predetermined moment during the pressure stroke of the piston.

Inasmuch as the fuel supply pump 26 supplies to the chamber more fuel than is ever taken from the chamber 2.5 during normal operation of the engine, the pressure in the chamber 25 increases during such operation. During such an increase in pressure the control member 30 is moved further against the influence of spring 31 until the annular groove 39 overlaps the-openingV 45 so that the excess amount of fuel supplied to chamber 25 from the fuel supply pump 26 may freely flow back to the tank 4d without first passing through the throttled portion of the bore 34.

It is possible to connect a distributor to the injection pump illustrated in the drawing, so that this pump can be used to supply fuel to a multi-cylinder engine.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of injection pumps differing from the types described above.

While the invention has been illustrated and described as embodied in automatically controlled injection pumps, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. An injection pump for an internal combustion engine, comprising, in combination, a pump housing formed in its interior with a cylindrical bore; means in said pump housing forming therein a fuel chamber separate from said cylindrical bore, said fuel chamber being adapted to be supplied with fuel by a fuel suppiy means which supplies fuel at a rate proportional to the speed of an'engine to which the injection pump is adapted to be operatively connected; a pump piston slidable in said cylindrical bore;

reciprocating means engaging said pump piston to reciprocate the same between bottom and top dead center positions; a free piston slidably mounted in said cylindrical bore for free movement therein and facing the head end of 'said pump piston so that said pistons define between themselves a pump chamber formed by that part of said cylindrical bore located between said pistons; limiting means forming part of said housing and limiting movement of said free piston toward said pump piston; rfirst passage means communicating with said fuel chamber and with a part of said pump chamber distant from said free piston for supplying fuel to the interior of said pump chamber when said pump piston moves in its suction stroke toward its bottom dead center position; second passage means adapted to lead to a cylinder of an engine and communicating with a part of said pump chamber adjacent said free piston for delivering fuel from said pump chamber and adapted to convey the fuel to the engine cylinder; third passage means communicating with said fuel chamber and with a part of said bore 1ocated at the side of said free piston opposite from said pump piston so that said free piston is located between said third passage means and said pump chamber; and passage control means carried by said housing at'said third passage means thereof and adapted to cooperate with said fuel supply means for automatically opening said third passage means, when the injection pump is connected to an engine, to an increasing extent as the engine speed increases and to a decreasing extent as the engine speed decreases until at low engine speeds said third passage means is closed and said free piston cannot move away from said pump piston while at relatively higher engine speeds said free piston may move away from said pump piston, displacing fuel through said third passage means into said fuel chamber, to reduce the amount of fuel moved by said pump piston through said second passage means to the engine cylinder.

2. An injection pump for an internal combustion engine, comprising, in combination, a pump housing formed in its interior with a cylindrical bore; means in said pump housing forming therein a fuel chamber separate from said cylindrical bore, said fuel chamber being adapted to be supplied with fuel by a fuel supply means which i supplies fuel at a rate proportional to the speed of an engine to which the injection pump is adapted to be operatively connected; a pump piston slidable in said` cylindrical bore; reciprocating means engaging said pump piston to reciprocate the same between bottom and top dead center positions; a free piston slidably mounted in said cylindrical bore for free movement therein and facing the head end of said pump piston so that said pistons dei-ine between themselves a pump chamber formed by that part of said cylindrical bore located between said pistons; limiting means forming part of said housing and limiting movement of said free piston toward said pump piston; first passage means communicating with said fuel chamber and with a part of said pump chamber distant from said free piston for supplying fuel to the interior of said pump chamber when said pump piston moves'in its suction stroke toward its bottom dead center position; sec` ond passage means adapted to lead to a cylinder of an engine and communicating with a part of said pump chamber adjacent said free piston for delivering fuel from said pump chamber and adapted to convey the fuel to the engine cylinder; third passage means communicating with said fuel chamber and with a part of said bore located at the side of said free piston opposite from said pump piston so that said free piston is located between said third passage means and said pump chambers; passage control means carried by said housing at said third passage means thereof and adapted to cooperate with said fuel supply t means for automatically opening said third passage means, when the injection pump is connected to an engine, to an increasing extent as the engine speed increases and to a decreasing extent as the engine speed decreases until at low engine speeds said third passage means is closed and said free piston cannot move away from said pump piston while atrelatively higher engine speeds said free piston may move away from said pump piston, displacing fuel saidtbore-attheside of said vfreepiston.oppositenirom said" pump pistonto limit movement of; saidfree. piston. away from saidtpumpplston.

3. An injection pump'for an .internal combustion. en@

gine, comprising, in combination, azpumpihousing formedA innits. interior with acylindrical here; means insaid pump.

housing forming therein a fuel chamber separate from saidcylindrical bore, saidzfuel chamber being adaptedlo be. supplied with fuel by afuel supply meausi Whichsup.-

plies fuel-atarate proportional to the speedtofran, engine towhich the injection pump is adapted totbefoperatively.

connected; .-a. pump piston. slidablefin. said: cylindrical bore; reciprocating means engaging saidpuanppistonlto reciprocatefthe same between bottom and top dead center posi.- tious; a free. piston slidably mounted.' in saidk cylindrical bore for free movement` therein and facing the head end o of-'said pump piston so that saidpistons define between themselves-ia pump` chamber formed by thatpart of saidcylindrical bore located between said pistons; limiting means forming *wart of said housing and limiting movement of said. free piston toward said pump piston; first.

passage. means communicating with said fuel chamber and' with a part of said'pump chamber distant from said@ free. piston forY supplying fuel to the interior of said pump chamber when said pump piston. moves inv itsv suction.

stroke toward its bottom dead center. position; second, passage means adapted to lead toa cylinder o an engine and communicating with a part of saidipurnp chamber' adjacent said free piston for delivering. fuel from saidpumpA Chamber and adapted to convey the fuel to the engineicylinder; third passage means;communicating'with saidsfuelchatnber. and with a part ot"V said bore locatedat theiside of. said free piston opposite from` said pump pis-4 ton` so that said free pistonis located;betweenv saidvthird. passage means and said-pump chamber; passage controlf means-carried by said housing at'said third passage means thereof and: adapted to cooperate with said fuel supply means for automatically opening saidsthird. passage means,

when the injection pump is connected to ancngine, to anincreasing extent as the engine speedincreases and to a decreasing extent'as the engine speedrdecreasesuntil at low engine. speedssaid thirdpassage meansis closed and saldi free pistoncannot move away from said pump piston while atrelatively higher engine speeds said free piston may-move away from said pump piston, displacingfuelthrougltsaid.third-passage means into said fuel chamber, to reduce the amount of. fuel moved by said pump piston through said second passage means tothecngine cylinder;

stopJneanszcarriem by said housing and locatedin said bore;at thee side of said free pistonopposite fromsaid:

pump piston to limit. movement offsaid'free piston away from saidpurnp piston; andiadjustugmeans operatively connected tov saidstop means foradjusting. the position' ofthedatter-insaidcylindrical bore so as to regulate the extent to which said free piston may be moved away from said fpumppiston.

4; A- devicefor controlling the feeding of fuel to an internal combustion engineY comprising, in combination,

an-zinjection pump housing formed in its interior with a.

pairA of' elongatedv bores; means in said' pump housing formingthereinia uel chamber separatefrom one ofifsaid` bores; a pump piston slidable in saidone bore; reciproeating: means engaging said-pump .piston to reciprocate the same-in said'one bore between bottornand top dead-center positions: a free piston siidable inl said one bore for free movement therein andfacing the .headend'zofsaidpump piston so that: said pistons define between themselves a pump chamber formed by thatpart-of-said oney borelocated-between said-pistons; limiting means forming part OiSaid-ahousingand limitingv the movement'of said free piston towardsaid pump piston; tirstlpassage'meanscomnlutticatngfwitlr saidifel chamber--andfwithapart'of said pump chambendistanb from saidl freeipiston. for supplying; fueli-to the nteriorfosaid pumpYchamberfwhentsaidpump. piston; movesintits. sution stroke toward4 its: bottomt dead center position; second passage means adapted: to lead4 be acted; on.. by.: fueL` under.- pressure in'. said. chamber sor that theme11 undenpressure tends4 to move said' control member-'fromitsTposition,closingsaid third passageimeans;V spring meansgengaging, saidcontrol member. and urging. the. sameiozitscposition closing. said third/passage` means; and; aY fuel supply, pump communicating with, said -fuel chambersaud adapted: to be: connected to an engine to4 be driven thereby so that when said fuel supply. pump audisaid;injection:pumpv are operatively connected' to an engine; asithetengine speed increases thev fuel supply pump. tendsgtoideliven an increasing-amount'of fuel to said. fuel; charnbenv to increase. the pressure therein and. move-said' controbmemben against-.the-influence.of'said spring means awaygfrorn its closed-f position, whereby. said third passageb means*x is; opeuedato ani increasingv extent: as the engine speedincreasestandto aV decreasing. extent as the engine speedgdecreasess.

5. device: for: controlling. the feeding of fuel to an internal combustion engine comprising, ink combination, an= injection; pump. housing. formed in itsinterior withA a pali-'ofi elongatedv bores; means'. in said pump housingl forming thereinf a fuelt chamber separate from4 one` ofV saidbores;.aipump pistonslidable insaid one bore;.recip rocatingimeansfengagingfsaidtpump piston-to reciprocatethesamenintsaid:onebore betweentbottom and top dead; center positions; a free piston slidablev in saidone borefor. freemovement-z therein and:facingv the head end of said .fpumpipistoniso that said pistons define betweeny them; selves; a: pump .chamber formed:by thatpart or saidonei boreflocatedtbetvveen,said pistons; limiting means formf-Y ingy part ofi saidv housing. and f limiting .l the movement'A of. said tree piston toward said pump piston; tirstpassage:y means communicating with. saidiluelA chamber andwith a=partloffsaid pump chamber'distantsfrom said free pistonfm1-'supplying.fuel/.tofr the; interior of, said pump chamber-l when said'pumppistorrmovesin.its suctionstroke towardits@ bottom', dead centerposition; second passagemeans; adapted toalea'ditoacylinder oan engine. and communif catingfwithiatpartiof. said.purnp=chamber. adjacent said freeipiston forrdelivering fuel fromsaid purnpnehamber` and adapted to conveyl the. fuel to the engine-cylinder; thirdt-passagerneanscommunicating with said'fuel chamber and with a part of said one bore locatedat the-.side oft said;freepistoncpposite from said pump piston so thatsaid free-pistonis -locatedbetween said third passage4 meanszand; said i pump chamber, said Y' third. passage ,meansextending-1 acrossand bjeingintersccted bythe: other. of. said bores; an-elongated-control membervslidable insaid: other; bore for movement to and from a: position entend;` ing acrossmnd vclosingsaid third; passage means,- saidcon-` t trohmernber having-a` transverse surface communicating..

withzsaid fuelzchamberftobe' actcdion' by fuel undertpres-i surein said' chamberfso' that-'the fuel under fpressuretends'f to movesaid controlmemberfrom its position closing saidk third passage means; spring means engaging-said con trol'm'ember and urging-thesametoits position closingl` afrssaa said third passage means; a fuel supply pump communieating with said fuel chamber and adapted to be connected to an engine to be driven thereby so that as the engine speed increases the fuel supply pump tends to deliver an increasing amount of fuel to said fuel chamber .to increase the pressure therein and move said control member against the influence of said spring means away from its closed position, whereby said third passage means is opened to an increasing extent as the engine speed increases and to a decreasing extent as the engine speed decreases; and fourth passage means leading from said fuel chamber back to said fuel supply pump and having a throttling portion of reduced cross section which is small enough to allow the fuel to flow freely back toward the fuel supply pump, when the latter and said injection pump are operatively connected to an engine, only at engine speeds which are lower than the idling speed of the engine.

6. A device for controlling the feeding of fuel to an internal combustion engine comprising, in combination, an injection pump housing formed in its interior with a pair of elongated bores; means in said pump housing forming therein a fuel chamber separate from one of said bores; a pump piston slidable in said one bore; recipro eating means engaging said pump piston to reciprocate the same in said one bore between bottom and top dead center positions; a free piston slidable in said one bore for free movement therein and facing the head end of said pump piston so that said pistons define between themselves a pump chamber formed by that part of said one bore located between said pistons; limiting means forming part of said housing and limiting the movement of said free piston toward said pump piston; first passage means communicating with said fuel chamber and with a part of said pump chamber distant from said free piston for supplying fuel to the interior of said pump chamber when said pump piston moves in its suction stroke toward its bottom dead center position; second passage means adapted to lead to a cylinder of an engine and communicating with a part of said pump chamber adjacent said free piston for delivering fuel from said pump chamber and adapted to convey the fuel to the engine cylinder; third passage means communicating with said fuel chamber and with a part of said one bore located at the side of said free piston opposite from said pump piston so that said free piston is located between said third passage means and said pump chamber, said third passage means extending across and being intersected by the other of said bores; an elongated control member slidable in said other bore for movement to and from a position extending across and closing said third passage means, said control member having a transverse surface communicating with said fuel chamber to be acted on by fuel under pressure in said chamber so that the fuel under pressure tends to move said control member from its position closing said third passage means; spring means engaging said control member and urging the same to its position closing said third passage means; a fuel supply pump communicating with said fuel chamber and adapted to be connected to an engine to be driven thereby so that as the engine speed increases the fuel supply pump tends to deliver an increasing amount of fuel to said fuel chamber to increase the pressure therein and move said control member against the influence of said spring means away from its closed position, whereby said third passage means is opened to an increasing extent as the engine speed increases and to a decreasing extent as the engine speed decreases; and fourth passage means leading from said fuel chamber back to said fuel supply pump and having a throttling portion of reduced cross section which is small enough to allow the fuel to ow freely back toward the fuel supply pump, when the latter and said injection pump are operatively connected to an engine, only at engine speeds which are lower than the idling speed of the engine, said fourth passage means having a first portion communicating with said other bore and a second portion extending along the interior of said' elongated control member, and said throttling portion of said fourth passage means being located within said control member.

7. An injection pump for an internal combustion engine, comprising, in combination, a pump housing formed in its interior with a cylindrical bore; means in said pump housing forming therein a fuel chamber separate from said cylindrical bore, said fuel chamber being adapted to be supplied with fuel by a fuel supply means which supplies fuel at a rate proportional to the speed of an engine to which the injection pump is adapted to be operatively connected; a pump piston slidable in said cylindrical bore; reciprocating means engaging said pump piston to reciprocate the same between bottom and top dead center positions; a free piston slidably mounted in said cylindrical bore for free movement therein and facing the head end of said pump piston so that said pistons define between themselves a pump chamber formed by that part of said cylindrical bore located between said pistons; limiting means forming' part of said housing and limiting movement of said free piston toward said pump piston; first passage means communicating with said fuel chamber and with a part of said pump chamber distant from said free piston for supplying fuel to the interior of said pump chamber when said pump piston moves in its suction stroke toward its bottom dead center position; second passage means adapted to lead to a cylinder of an engine and communicating with a part of said pump chamber adjacent said free piston for delivering fuel from said pump chamber and adapted to convey the fuel to the engine cylinder; third passage means communicating with said fuel chamber and with a part of said bore located at the side of said free piston opposite from said pump piston so that said free piston is located between said third passage means and said pump chamber; fourth passage means communicating with the interior of said fuel chamber and with said part of said bore located at the side of said free piston opposite from said pump piston; pressure-operated nonreturn valve means located insaid fourth passage means for allowing fuel to tow from said fuel chamber along said fourth passage means into said bore whenever the difference in pressures on opposite sides of said nonreturn valve opens the latter; and passage control means carried by said housing at said third passage means thereof and adapted to cooperate with said fuel supply means for automatically opening said third passage means, when the injection pump is connected to an engine, to an increasing extent as the engine speed increases and to a decreasing extent as the engine speed decreases until at low engine speeds said third passage means is closed and said free piston cannot move away from said pump piston while at relatively higher engine speeds said free piston may move away from said pump piston, displacing fuel through said third passage means into said fuel chamber, to reduce the amount of fuel moved by said pump piston through said second passage means to the engine cylinder.

8. A device for controlling the feeding of fuel to an internal combustion engine comprising, in combination, an injection pump housing formed in its interior with a pair of elongated bores; means in said pump housing forming therein a fuel chamber separate from one of said bores; a pump piston slidable in said one bore; reciprocating means engaging said pump piston to reciprocate the same in said one bore between bottom and top dead center positions; a free piston slidable in said one bore for free movement therein and facing the head end of said pump piston so that said pistons dene between themselves a pump chamber formed by that part of said one bore located between said pistons; limiting means forming part of said housing and limiting the movement ot' said free piston toward said pump piston; first passage means communicating with said fuel chamber and with a part of said pump chamber distant from said free piston 141 for. supplying fuel to` the inteu'orrof'saidf pump chamber when` said pump pistorr moves` inl itsl suction* sti-voltel towardits: bottom dead: center position", second@A passage means adapted to lead to a cylinder of an engine and' communicating with a part of saidi pump chamber adjacentsaidifreezpiston for delivering fuel froml said pump chamber anchL adaptedf toA conveyA the fuel! toAJ the engine cylinder; third. passage means communicating with said? fuelchamber and witha part of said one bore locatedat the sid'eofsaid free pistonfoppositef from saidpumppiston'- so that' saidifree pistonz is locatedl between said third passagetrneansY and! said pumpchamber, saidthird passage means extending'acrossandfbeing: intersected'by the other off said'l bores; an elongatedf controli member slidable: in saidother bore'frmovement to-andlfromapositi'on ex tending across and 'closingv said third ypassage means, said control member. having aI transverse surface communicat-Y ing'withrsaidfuellchamber tobe acted on byffuel under pressure insaitlI chamber so=thatfthe fuel under pressurel tends to xmove said controlmemberfrom' itslposition cl'os-V ing said third passage means-' spring-means-engaging said control' membert and' urging tlesamelt'cr itsposition clos'- ingsaid third passage means; a fuelx supply purnp come municating with-said fuel chamber and adaptedto'be con nectedto-an engineto be driven thereby so thatas tlie engine speed? increases the fueli supply'pump tendsto deliver an' increasing' amount of fuel tof-said fuely chamber' tofincrease the-pressure thereiny and' move said control member against the influence of saidspring means away' from litsl closed position, whereby saidthird passagemeans is opened to an increasingextent as the'engine-speedtin'- creases-'audio a decreasing extent as'the engine speed-de`- creases; andlfourth passage meansleading from' sa'id'onex bore hack' tol said`- fuelsupply pump; extendingI across said other lore, and saidrcontrol memherljaving-.a por; tienA extending acrossf and closingsaidAr fourth: passage'v means when'said control4v member closes saidtlii'dpas sagerneans.

No referencescited. 

